Tachykinins are a family of peptides which share a common amidated carboxy terminal sequence. Substance P was the first peptide of this family to be isolated, although its purification and the determination of its primary sequence did not occur until the early 1970's.
Between 1983 and 1984 several groups reported the isolation of two novel mammalian tachykinins, now termed neurokinin A (also known as substance K, neuromedin L, and neurokinin .alpha.), and neurokinin B (also known as neuromedin K and neurokinin .beta.). SEE J. E. Maggio, Peptides, 6 (Supplement 3):237-243 (1985) for a review of these discoveries.
Tachykinins are widely distributed in both the central and peripheral nervous systems, are released from nerves, and exert a variety of biological actions, which, in most cases, depend upon activation of specific receptors expressed on the membrane of target cells. Tachykinins are also produced by a number of non-neural tissues.
The mammalian tachykinins substance P, neurokinin A, and neurokinin B act through three major receptor subtypes, denoted as NK-1, NK-2, and NK-3, respectively. These receptors are present in a variety of organs.
Substance P is believed inter alia to be involved in the neurotransmission of pain sensations, including the pain associated with migraine headaches and with arthritis. These peptides have also been implicated in gastrointestinal disorders and diseases of the gastrointestinal tract such as inflammatory bowel disease. Tachykinins have also been implicated as playing a role in numerous other maladies, as discussed infra.
Tachykinins play a major role in mediating the sensation and transmission of pain or nociception, especially migraine headaches. See. e.g., S. L. Shepheard, et al., British Journal of Pharmacology, 108:11-20 (1993); S. M. Moussaoui, et al., European Journal of Pharmacology, 238:421-424 (1993); and W.S. Lee, et al., British Journal of Pharmacology, 112:920-924 (1994).
In view of the wide number of clinical maladies associated with an excess of tachykinins, the development of tachykinin receptor antagonists will serve to control these clinical conditions. The earliest tachykinin receptor antagonists were peptide derivatives. These antagonists proved to be of limited pharmaceutical utility because of their metabolic instability.
Recent publications have described novel classes of non-peptidyl tachykinin receptor antagonists which generally have greater oral bioavailability and metabolic stability than the earlier classes of tachykinin receptor antagonists. Examples of such newer non-peptidyl tachykinin receptor antagonists are found in U.S. Pat. No. 5,328,927, issued Jul. 12, 1994; U.S. Pat. No. 5,360,820, issued Nov. 1, 1994; U.S. Pat. No. 5,344,830, issued Sep. 6, 1994; U.S. Pat. No. 5,331,089, issued Jul. 19, 1994; European Patent Publication 591,040 A1, published Apr. 6, 1994; Patent Cooperation Treaty publication WO 94/01402, published Jan. 20, 1994; Patent Cooperation Treaty publication WO 94/04494, published Mar. 3, 1994; and Patent Cooperation Treaty publication WO 93/011609, published Jan. 21, 1993.
Interstitial cystitis is a chronic debilitating inflammatory disorder of the bladder. The disease is most common in women ranging in age from about thirty to sixty with onset of the condition typically occurring at about forty years of age. It is characterized by a number of urinary difficulties, such as suprapubic pressure and pain, with bladder filling, urinary frequency, nocturia, dysuria, urgency adn irritative voiding associated with morphological and histological changes in the bladder. The condition is characterized as "interstitial cystitis" because it is believed the condition does not affect the surface of the bladder, but instead involves the spaces between the cells, namely the interstices, in the lining of the bladder.
Urethral syndrome is a related painful voiding disorder of unknown etiology affecting women exhibiting many of the conditions set forth above.
As noted in U.S. Pat. No. 5,145,859, issued Sep. 8, 1992, the entire contents of which are herein incorporated by reference, there are a number of compounds proposed to treat these conditions, based on differing theories as to the etiology of interstitial cystitis and urethral syndrome. None of these treatment regimens has proven completely successful to date.
Because of the current dissatisfaction of the currently marketed treatments for interstitial cystitis within the affected population, there exists a need for a more efficacious and safe treatment.